On various forms of mobile platforms, and particularly on commercial aircraft, In-Flight Entertainment (IFE) systems are required to send video streams to an aircraft passenger's video display unit, and synchronized audio streams to a headphone jack in a passenger's PCU (Passenger Control Unit) or to some other audio speaker. Typically, the video display is located in the seatback of a seat disposed in a first seat row. The audio signal that is associated with the video content displayed on the video display, however, typically needs to be supplied to an audio jack or speaker that is typically located in a seat in a second seat row behind the first seat. Thus, the video and audio streams must be delivered to two separate network “clients”, but still played in near-perfect synchronization. This is considerably different than the typical network or internet situation where the video and sound signals are played on the same client/host apparatus.
In the past, IFE systems have generally been hard-wired systems. The audio and video signals have been delivered as analog or digital signals to one or the other of the first or second seats described above. Feedforward or feedback cables have been used to send the analog signal to the “other half” of the client. For example, if the audio and video signals were delivered to the first seat, then feedback cables were used to supply just the audio signal to the audio jack or speaker associated with the second seat.
With modern systems, there is a strong desire to move towards completely wireless, digital delivery of both video and audio signals to all of the seats within a mobile platform, such as within a commercial aircraft. Often the video and audio streams are compressed before being transmitted from a wireless access point (or points) within the cabin of the mobile platform to the seats. With this arrangement, the video and audio streams must be decompressed/decoded at the “client end” of the network connection (i.e., at least at one seat location). One option would be to send the video and audio streams separately to the two clients (or the combined stream to both clients). However, in that situation the separate decoding at the two clients can lead to audio playout that is out of synch with the video playout. Therefore, it is desirable to decode both video and audio at one client, and then send decoded audio or video to the “other half” of the client (i.e., to the other seat that did not initially receive both streams of information). It would be highly desirable to accomplish the feedforward/feedback of one or the other of video or audio signals without the use of electrical cables. Eliminating the use of electrical cabling for the feedback information stream being transmitted to one of the seats would enable a completely wireless system to be implemented. This would save cost and weight, and reduce the complexity of installation of an IFE system within a mobile platform.